A lot of this comes down to the specific student: what does he like, what is she especially good at, what is she especially bad at, any diagnosed issues, how mature, any real goals yet, what can the school offer, are there financial constraints, is homeschooling an option, what has already worked or failed, et cetera, ad infinitum. Meet the kid where he is, see where he wants to go, make sure he’s as functional as possible in his weak areas, make sure he has room to grow in his strengths.
OP, I’d let him walk through HS, but explain that by doing so he’s making a lot of other choices at the same time. Make him map out a full path from this year through college and grad school. What classes, what major, what schools, and then point out the gaps where the plan won’t work. Top schools don’t need to settle for kids that could do better whenever they want to, they choose the kids that have shown what they can do. (And if he thinks high school is boring and not worth the effort just wait until he’s paying $60k to scoff at the same math classes he won’t take now. )